Zircon refractory compositions

ABSTRACT

A new refractory composition from 85.0 percent to 98.8 percent zircon, from 1.0 percent to 8.0 percent chromic oxide and from 0.2 percent to 5.0 percent titanium dioxide has been prepared which has a low porosity, a high modulus of rupture and has a high resistance to corrosion by molten metals.

United States Patent [191 Manigault Apr. 16, 1974 ZIRCON REFRACTORY COMPOSITIONS Prima Examiner-James E. Poer 75 1 ent r. Edw dL.Mani ltC t, 1 0 Ohio" gnu mcmnal Attorney, Agent, or Firm-Robert L. Lehman [73] Assignee: The Chas. Taylor's Sons Company,

- Cincinnati, Ohio 22 Filed: Dec. 20, 1972 [57] ABSTRACT [21] Appl' 316mm A new refractory composition from 85.0 percent to 98.8 percent zircon, from 1.0 percent to 8.0 percent [52] US. Cl. 106/57, 166/66 chromic oxide and from 0.2 percent to 5.0 percent ti- [51] Int. Cl. C04b 35/12, C04b 35/16 tanium dioxide has been prepared which has a low po- [58] Field of Search 106/57, 65, 66 rosity, a high modulus of rupture and has a high resistance to corrosion by molten metals.

[56] References Cited UNITED STATES PATENTS 2 Claims, No Drawings 5/1965 Thomas 106/57 ZIRCON REFRACTORY COMPOSITIONS BACKGROUND OF THE INVENTION Both the chromic oxide and the rutile were 325 mesh size.

3 kg of an organic binder and 1.1 kg of water were mixed with the above ingredients to temper the mix- Rutile, kg

Many types of ceramic compositions have been pre- 5 ture. The mixture was then formed into bricks 9 inches pared in the past which have given good service in glass X 4% inches X 3 inches and were fired at 1,560C for contact and back-up linings for the glass industry. One 5 hours. v I g particular type of ceramic composition which is partic- The fired bricks had the following properties: ularly useful is the so-called zircon brick which may consist of from 96% to 99% zirconium silicate, and 10 from 1% to 4% other oxides. Although these zircon r ig f g 2 bricks are commercially useful, it has been found that Absorp t i on, at 3:9 the composition may be modified to produce a superior Denim type of brick which has an increased modulus of rupture, an increased bulk density and a decreased poros- Thesipro'pertles' are Supenor to a typlcfll standard ity. In addition, the brick is more resistant to penetra- Zircon brick which possesses the following proper tion by metal and metallic oxide often present when tramp metal is unintentionally introduced in the glass batch with recycled glass. This new refractory is Modulus of Rupture psi 2300 particularly useful as a back-up, or sub-floor, under the Porosity, as 17.5

glass contact bottom blocks in a glass-melting tank. g/cc SUMMARY OF THE INVENTION In order to show the bricks resistance toward pene A new ceramic composition has been produced tration of tramp metal into the brick, the following test prising from 85.0% to 98.8% zircon, from 1.0% to 8.0% was f chromic oxide and from 0.2% to 5.0% titanium diox- A f black Steel nut was f i on the Surface ide, all of the percentages expressed on a weight basis. of i bnck produced and bnck was heated to Such a composition when fired between 1,450C and C for Afier cooling. the depth of pine- I6OOOC produced bricks and other shapes which have tration of the iron oxide into the brick was measure as superior properties to those obtained from the well- 039 known briclm For comparison a prior art Zll'COl'l. brick was sub ected to the same test and it was found that the depth of pen- DESCRIPTIQN OF THE PREFERRED etration was 2% inches.

EMBODIMENTS W It has been found that when small amounts up to EXAMPLES 24 8.0% chromic oxide are added as a modifying agent, In these examples the procedure of Example 1 was that superior results are obtained over zircon bricks t d except h varying amounts of h i dicontaining no chromic OXid ents were employed. The amounts of ingredients used In preparing the new refractory composition of the and the results obtained are recorded in the table along instant invention, the zircon (zirconium silicate) is 40 with those of Example 1 and the prior art zircon sized to 70 mesh. The chromic oxide and the titanium bricks. dioxide are ground to -325 mesh size. Examples 2 and 3 contained chromic oxide in The three ingredients are thoroughly mixed with amounts of 2.0 and 4.2% respectively while in Example water and lignin liquor to temper the mixture and the 4 an amount of 10.0% was used which lies outside the mixture is then pressed into shapes and fired at a temrange of chromic oxide addition. perature between 1,450C and l,600C. From the table it has clearly been shown that the when the instant r ry P d is mp re bricks formed using amounts of chromic oxides which with the zircon prior art products, it has been found fall within the range of the instant invention produce t th general P y a P operties of the instant prodover-all superior results to those obtained by the prior uct are improved. The bulk density and the modulus of art zircon bricks. The products possessed superior rupture are both increased while the porosity is demodulus of rupture, increased bulk density, decreased creased. The instant refractory product is also more reporosity and greater resistance toward iron penetration sistant to iron oxide penetration than the prior art prodthan the zircon bricks of the prior art. Example 4 which uct. was an excessive amount of chromic oxide produced In order to describe more fully the instant invention, inferior modulus of rupture and porosity. the following examples are presented: While this invention has been described and illustrated by the examples shown, it is not intended to be EXAMPLE 1 strictly limited thereto, and other variations and modi- 93.5 kg of zircon mesh) were mixed with 6 kg fications may be employed within the scope of the folof chromic oxide and 0.5 kg of rutile titanium dioxide. lowing claims.

TABLE 1 EXAMPLE No. PRIOR-ART lNGREDlENTS l 2 3 4 ZIRCON BRICK Zircon, kg 93.5 98 95.4 99 Chromic Oxide, kg 6 2.0 4.2 10

TABLE 1onti nued EXAMPLE No. PRIOR-ART INGREDIENTS I 2 3 4 ZIRCON BRICK PROPERTIES Modulus of Rupture, psi 3270 3336 3514 2026 2300 Porosity. b 15.5 16.8 15.8 19.2 17.5 Absorption, l: 3.9 4.3 4.1 5.0 3.72 Bulk mg/ 3.95 3.87 3 87 3.80 2 12 Nut test, Depth of 0.39 78 2:13

penetration, iggh es I claim:

1. A refractory composition comprising from 85.0% to 98.8% zircon, from 1.0% to 8.0% chromic oxide and from 0.2% to 5.0% titanium dioxide, all percentages expressed by weight, said composition having a high modulus of rupture and low porosity, said refractory composition prepared from zircon particles 70 mesh in size and chromic oxide and titanium dioxide particles --325 mesh in size.

2. A method for preparing a refractory composition having a high modulus of rupture and low porosity which comprises thoroughly mixing zircon, chromic It l 8 i 

2. A method for preparing a refractory composition having a high modulus of rupture and low porosity which comprises thoroughly mixing zircon, chromic oxide and titanium dioxide, the amount of zircon employed being from 85.0% to 98.8%, the amount of chromic oxide being from 1.0% to 8.0% and the amount of titanium dioxide being from 0.2% to 5.0%, all percentages expressed by weight, said zircon being -70 mesh in size and said chromic oxide and said titanium dioxide being -325 mesh in size, forming the mixture into a ceramic shaped body, and firing the shaped body at a temperature from 1,450*C to 1,600*C to produce said refractory composition. 